Semiconductor devices, such as microprocessors, memory devices, and other microelectronic computer "chips", are typically produced from a thin, flat, circular disk of material, often referred to as a silicon wafer. A large number of identical microelectronic structures are created on a single wafer and the wafer is then cut into individual devices, whereupon each device is packaged for sale as a chip.
During the manufacture of such semiconductor devices, a series of layers are typically produced on the surface of a wafer. A layer of microelectronic structures may be applied to the wafer surface through the use of, for example, optical lithography, as is well known in the art. In the production of integrated circuits, a plurality of interrelated layers of microelectronic structures are superimposed on the surface of the wafer, with a layer of a dielectric interposed between and separating each of the microelectronic layers. Proper application of a microelectronic layer requires a smooth, highly planar surface. Thus, after each layer of dielectric is applied to a workpiece, the workpiece is planarized through the use of, for example, a chemical mechanical planarization (CMP) machine.
The production of semiconductor devices requires a high degree of purity; hence, powerful and mature clean room manufacturing techniques have been developed. An integral component of clean room fabrication processes is a thorough cleaning of wafers after each planarization, polishing, or other process. A typical cleaning operation passes wafers through a series of scrub rollers, whereupon the wafers are rinsed to remove all particles from the wafer surfaces. After rinsing, the wafers must be dried prior to storage and/or transportation to subsequent processing step(s).
Presently known spin dry systems rely on centrifugal forces which result from spinning wafers at high velocities (e.g., 2,700 to 5,000 rpm) to drive water droplets radially outward from the wafer surfaces, and to thereby liberate all water from the wafer surfaces. The drying of a wafer after cleaning is typically accomplished by placing the wafer on a platform and spinning the platform at a high velocity, for example on the order of 1,000-3,000 rpm, to liberate all rinse water and any residual particles from the wafer surfaces. As a result of these high process velocities, presently known spin drying systems typically confront the following two concerns:
I) the need to protect operators and equipment from disk fragments which could be thrown from the spin dryer in the event that a disk is broken during the spin dry process; and PA1 ii) the need to prevent water thrown from disks during the drying process from contacting disks which have already been dried.
In many prior art systems, these two needs are addressed by isolating the spinner, for example through the use of a shield, compartment, or the like.
Presently known spin dry systems are unsatisfactory in several regards. As spin rates increase, for example, stresses on and in the wafers being spun also increase, resulting in enhanced risks of wafer damage. Moreover, attempts to shield spinning wafers from operators and adjacent equipment tend to increase the "footprint" of the cleaning and/or drying machine thereby increasing the cost of capital equipment acquisition and maintenance. Such costs become particularly high in a clean room environment.
As semiconductor manufacturers are experiencing increased pressure to increase throughput in response to the growing demand for computer chips, it is also desirable to decrease the time required to dry rinsed wafers. In view of the aforementioned circumstances, however, it is problematic to simply increase the spin rate to thereby decrease drying time.